Humming/buzzing sound at idle. Trans cooling lines?

A5/S5/RS5
#1

I’ve held off for more than a week before introducing this topic. I have searched around several forums with a little success, but no feedback… I have had my RS5 now for about 3 weeks, and when fully warm, and at idle, there is a distinct “humming” that I can hear and even feel through the steering wheel. From RS246.com and also AudiWorld.com where I found a thread about DSG whine, this may be transmission cooling lines touching/vibrating somewhere against the body, but can someone suggest where to start? Have you experienced this and resolved it? I know I have to start by removing the large panel underneath since there is “nothing” to see or touch otherwise :thinking:

Suggestions or photos would be greatly appreciated, as I am willing to fix by myself!

Here’s what DarkPhantom said in AW back in 2018:

I have a 2015 RS5 and the transmission has a irritant whining noise when in idle mode. The dealer already installed some deflectors to reduce the noise, which became tolerable for 5K miles.

Now the noise is even louder and they said it’s a normal DSG noise, and they will order other deflector, but I’m afraid that will not solve the issue.

Have anyone experienced similar issue?

#2

I believe BuyTheWarranty had this issue. But yes, it’s fairly common although I have not experienced it myself. The ATF coolant lines run by and in some places touch the heat shielding. If it’s at juuuust the right gap, it’ll vibrate. Simply need to reposition or secure the lines a bit better.

Given the fact you can feel it through your steering wheel, my money would be towards two hard parts coming into contact with one and other when they shouldn’t.

You do not have an aftermarket exhaust correct? I’d take a look at the exhaust as well, can come into contact with some of the cross braces underneath the car if not installed in the correct position.

#3

No aftermarket exhaust. It has the Sports exhaust, but I doubt that really means anything different up front… I guess it will be an exploratory mission once the “belly pan” is removed!

#4

I also have this little annoyance. It’s only present when in Drive, never in park. I only hear it at idle or when less than 5 mph. It sounds like someone’s tossing rocks at an empty soda can. I’ll be installing new pads and an exhaust soon and will see if I can locate it then.

#5

100% transmission cooler line rattling on heat shield. Took it to Audi a few times and they couldn’t “find it” and I also recorded a video. Others have posted videos on the other forum and yes it’s a slight buzz.

Ha, still have the video can hear it at 5seconds:

Was less noticeable with exhaust.

Was 100% fixed when installing the RMR cooler as they had to move things around for the front mounted cooler.

With the flywheel, headers and exhaust you wouldn’t be to hear it now either way!

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#6

Yes, pretty sure I can hear and agree on it being the same! When any throttle is given it is either masked or it “disappears”…

And sure headers, exhaust or other mods would likely mask the sound :smiley: enough that most people would never know. A little warmer weather here and I will put the car on ramps outdoors and get under there to see what I can do to reduce or eliminate it! I’ve been “window shopping” on RMR’s site and that oil cooler kit may be in my 2021 future…

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#7

I noticed this same problem. Very annoying.

#8

I plan to investigate this next week as I am having a mini vacation to work on the car, the lawn mower and even the snowblower!

I will be looking for locations where the trans cooler lines might be vibrating against body or other components. I will report if I resolve anything.

Last comment. I had to get my Euro garage to air chisel loose all 3 rear Triple Square bolts for the belly pan (under motor) as all were seized and heads already stripped. Replaced with something better and with anti seize applied!

#9

Okay, time for an update. It’s been a fun couple of days figuring out how to remove all those under panels of the RS5. The large metal one has so many different fasteners, and it was surprising to see how many needed to be removed from inside the wheel arches. The rear (gearbox) panel was simple compared to that, and finally the very front one below the radiator was a little tricky to release some “flaps” that prevented it from sliding rearward.

There was a lot of grit, sand, mud and even small rocks/pebbles on the corners of the large engine cover, now all washed clean.

The mission of course was to check/verify the ATF cooling lines, and are they ever difficult to follow or even see visually!!! Not fun! In any case, I THINK (well, so far…) that I have reduced or removed that humming sound by slightly moving the metal pipe where it loops over the LHS front axle shaft. This is just outboard of the inner CV joint, and the pipe is clamped there with a bolt. All I have done so far is slight PULL the pipe away from the frame rail here, and I can now barely hear that “hum” when I hopped back into the vehicle (still running).

I think I am satisfied but I will leave all these panels off for the next week while I do a little more driving around town. Hopefully this is resolved (at least to my satisfaction!).

Now to order up the missing and damaged fasteners… a few of those plastic “Spreader Rivets” were already badly damaged, and a couple of screws completely missing.

[Update] Humming still there at idle. This is a job that needs two people, one in the driver’s seat to listen, and one to wiggle pipes underneath… now I need an assistant!

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#10

Drive down to sunny Los Angeles and I will be your assistant. LOL.

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